Ionic 3 Menu, big problem at the beginning


I want to implement next behaviour:

  1. Application starts with login/registration page.
  2. After login it opens page with ion-menu. In the menu will be for example 3 buttons.
  3. User pushs a button in the menu. On this stage I want to keep “humburger button”

I read about “persistent” menu, but behaviour of the application is very strange:
When users click on button in the menu - on next page I have “back button” and “humburger”
“Humburger” does not work. Back button workds but when we return to in the menu “button” that was pushed - is disappeared. (After reopen “menu” - it exists)

What is the rigth wat to open pages: .push(newPage) or setRoot(newPage)? (I read docs, but…)
If I change to setRoot(newPage) - “humburger” disappear.

I have another question:
What version of Ionic better to use for development now?
I worked with ionic v1 and it was fine. This was two years ago. But now I spent a lot of time for viewing videos/reading docs, and there are no results) Probably will be better to use old version?)